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IT34931: PREFETCHERS INFINITELY LOOPING IN SQLBSERVICELEAFREQUEST

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You can track all active APARs for this component.

 

APAR status

  • Closed as program error.

Error description

  • Prefetchers may infinitely loop in sqlbServiceLeafRequest if a
    table space?s prefetch size is set to 0. The infinite looping
    will appear to a user as Db2 utilizing a high amount of CPU
    (nearly 100%) while the database is otherwise idle.
    sqlbServiceLeafRequest is used to prefetch index leaf pages and
    their associated data pages, so this issue may be triggered by
    any workload that has index prefetching.
    
    A stack dump will show one or more prefetchers with a stack
    similar to the following:
    sqliBreakUpAndSendRequests
    sqlbServiceLeafRequest
    sqlbPFPrefetcherEntryPoint
    sqbPrefetcherEdu::RunEDU()
    

Local fix

  • Set the prefetch size for all table spaces to a non-zero value.
    This can be done with ?ALTER TABLESPACE <tablespace-name>
    PREFETCHSIZE <number-of-pages>?.
    

Problem summary

  • ****************************************************************
    * USERS AFFECTED:                                              *
    * All users.                                                   *
    ****************************************************************
    * PROBLEM DESCRIPTION:                                         *
    * See Error Description                                        *
    ****************************************************************
    * RECOMMENDATION:                                              *
    * Upgrade to 11.1.4.7                                          *
    ****************************************************************
    

Problem conclusion

  • Upgrade to 11.1.4.7
    

Temporary fix

Comments

APAR Information

  • APAR number

    IT34931

  • Reported component name

    DB2 FOR LUW

  • Reported component ID

    DB2FORLUW

  • Reported release

    B10

  • Status

    CLOSED PER

  • PE

    NoPE

  • HIPER

    NoHIPER

  • Special Attention

    NoSpecatt / Xsystem

  • Submitted date

    2020-11-13

  • Closed date

    2022-04-17

  • Last modified date

    2022-04-17

  • APAR is sysrouted FROM one or more of the following:

  • APAR is sysrouted TO one or more of the following:

    IT36337

Fix information

  • Fixed component name

    DB2 FOR LUW

  • Fixed component ID

    DB2FORLUW

Applicable component levels

  • RB10 PSN

       UP

[{"Business Unit":{"code":"BU058","label":"IBM Infrastructure w\/TPS"},"Product":{"code":"SSEPGG","label":"DB2 for Linux- UNIX and Windows"},"Platform":[{"code":"PF025","label":"Platform Independent"}],"Version":"11.1","Line of Business":{"code":"LOB10","label":"Data and AI"}}]

Document Information

Modified date:
04 May 2022